Proving that age is just a number, two runners tackle the odds and break records at this weekend's races.

This past weekend was an epic one in running with both the young and the old coming out to shine — and break a few records while they're at it.

In Alexandria, Virginia, 10-year-old Reinhardt Harrison set a new world record for the fastest half marathon run by a 10-year-old. The tween ran the race in 1:35:02, a phenomenal time and about 2 minutes faster than the previous record. And get this: Harrison wasn't even running at his top speed because his dad insisted that the boy uses this race, his first half-marathon, as a training run.

Harrison's dad told various media outlets that his boy has been begging to run a half-marathon pretty much since the day he stopped crawling and started sprinting. He has been slowly and gradually building up mileage for the past several years to prepare for this race.

Across the coast, another runner was breaking records and making headlines for her age. In California, 91-year-old Harriette Thompson of North Carolina set a record in Sunday's Rock 'n' Roll San Diego marathon. Thompson finished her 26.2 mile run in 7:07:42, breaking the U.S. record for the fastest marathon run in the 90-94 age group. The previous record, set by a 90-year-old, was 8:53:08. Thompson became the second-oldest marathon finisher in U.S. history — the oldest was 92 years old.

Thompson is also a cancer survivor who runs every year to raise money for the Leukemia and Lymphoma Society and Team In Training. According to Runner's World, she has raised more than $90,000 for the cause.

What's even more extraordinary is that Thompson didn't even start running marathons until she was 76. She has run one marathon a year ever since, making Sunday's marathon her 15th. She told Runner's World magazine, "You're never too old to do it."